Re: [PATCH] plugins: add plugin API to get args passed to binary

[Alex Bennée]

"demin.han" <demin.han@starfivetech.com> writes:

> Why we need args?
> When plugin outputs log files, only binary path can't distinguish multiple
> runs if the binary passed with different args.
> This is bad for CI using plugin.

New APIs should come with an example use case for testing. However for
this use case why isn't the plugin using getpid() or gettid() a suitable
solution?

Some additional comments bellow...

> Signed-off-by: demin.han <demin.han@starfivetech.com>
> ---
>  include/qemu/qemu-plugin.h   | 11 +++++++++++
>  plugins/api.c                | 16 ++++++++++++++++
>  plugins/qemu-plugins.symbols |  1 +
>  3 files changed, 28 insertions(+)
>
> diff --git a/include/qemu/qemu-plugin.h b/include/qemu/qemu-plugin.h
> index 622c9a0232..daf75c9f5a 100644
> --- a/include/qemu/qemu-plugin.h
> +++ b/include/qemu/qemu-plugin.h
> @@ -837,6 +837,17 @@ bool qemu_plugin_bool_parse(const char *name, const char 
> *val, bool *ret);
>  QEMU_PLUGIN_API
>  const char *qemu_plugin_path_to_binary(void);
>  
> +/**
> + * qemu_plugin_argv_to_binary() - argv to binary file being executed
> + *
> + * Return a string array representing the argv to the binary. For user-mode
> + * this is the main executable's argv. For system emulation we currently
> + * return NULL.

Maybe more explicit:

qemu_plugin_get_user_argv() and be clear it is user mode only.

Although I suspect a qemu_plugin_get_user_env() might be a more useful
helper depending on the use case.

> The user should g_free() the string array once no longer
> + * needed.
> + */
> +QEMU_PLUGIN_API
> +const char **qemu_plugin_argv_to_binary(void);
> +
>  /**
>   * qemu_plugin_start_code() - returns start of text segment
>   *
> diff --git a/plugins/api.c b/plugins/api.c
> index 24ea64e2de..fa2735db03 100644
> --- a/plugins/api.c
> +++ b/plugins/api.c
> @@ -485,6 +485,22 @@ const char *qemu_plugin_path_to_binary(void)
>      return path;
>  }
>  
> +const char **qemu_plugin_argv_to_binary(void)
> +{
> +    const char **argv = NULL;
> +#ifdef CONFIG_USER_ONLY
> +    int i, argc;
> +    TaskState *ts = get_task_state(current_cpu);
> +    argc = ts->bprm->argc;
> +    argv = g_malloc(sizeof(char *) * (argc + 1));

 argv = g_new0(char *, argc + 1);

> +    for (i = 0; i < argc; ++i) {
> +        argv[i] = g_strdup(ts->bprm->argv[i]);
> +    }
> +    argv[argc] = NULL;

Allows you to drop this as well.

> +#endif
> +    return argv;
> +}
> +
>  uint64_t qemu_plugin_start_code(void)
>  {
>      uint64_t start = 0;
> diff --git a/plugins/qemu-plugins.symbols b/plugins/qemu-plugins.symbols
> index 032661f9ea..532582effe 100644
> --- a/plugins/qemu-plugins.symbols
> +++ b/plugins/qemu-plugins.symbols
> @@ -1,4 +1,5 @@
>  {
> +  qemu_plugin_argv_to_binary;
>    qemu_plugin_bool_parse;
>    qemu_plugin_end_code;
>    qemu_plugin_entry_code;

You can drop the symbols now we autogenerate them.

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro